The guinea pig will be developed as an animal model of pulmonary hypersensitivity to small airborne industrial chemicals. To define the conditions providing maximum sensitization, small chemicals (haptens) will be covalently linked to carrier protein molecules, and the resulting hapten-protein conjugates used as antigens. Hapte-specific respiratory hypersensitivity occurring either immediately or several hours following exposure (delayed onset) to the allergen, will be assessed by analysis of pulmonary functions. For these determinations, the hapten will be coupled to a heterologous carrier. The influence of the following factors upon induction of hapten-specific pulmonary hypersensitivty will be determined: a) dose of allergen; b) number and length of daily exposures; c) interval between exposures. Using the conditions producing optimum hapten-specific hypersensitivity, various industrial chemicals will be aerosolized. Determination and comparison of the allergenic capabilities of the chemicals using dose-response and threshold concentration studies should allow prediction of safe levels for industrial workers. Histopathological examination of the sensitized respiratory tissue and skin test sites will provide indication of cell-mediated immunity. Serological evaluations will be routinely performed. Local and circulating hapten-specific antibodies will be assayed by the following techniques: radioimmunoelectrophoresis, enzyme-linked immunosorbent assay, passive cutaneous anaphylaxis, and passive leukocyte sensitization. In this way a possible relationship between an in vitro immunological assay and the state of pulmonary hypersensitivity as ascertained by bronchial provocation should become apparent.